Measuring the percentage of forest canopy which is now an important and practical criterion because the Horizontoscope and measuring methods are not useful, by utilization of Aerial photographs which is very costly and difficult with estimation without the use of any device in most cases it is measured.
Two main methods to measure the percentage of forest canopy are as follows:                1. It is supplied by the device called Horizontoscope that according to the image it took from the canopy and the space crown of trees had been analyzed by the software in the office with the number of canopies. By Horizontoscope's method, it's very time-consuming and do not perform in the forest and necessary facilities are not available for analysis. Also, it doesn't immediately get provided to the expert.        2. It is determined by Visual approach and using people's experience and skillful experts due to the density and estimated shortness canopy, that is just based on experience and information that has emerged over time. The visual approach is not accurate, not everyone can use this method because there is no sufficient knowledge and experience to do it and different teachers got different numbers and there is a possibility of error.        3. Aerial photos method because of being costly and lack of access speed and specialty was not useful. Now, the device has been fixed all the defects of the methods such as heaviness, cost, low speed and lack of access and the public's understanding of the method of calculation.        